Getting Wifi and Bluetooth working on your Dell E5540 with AR9285 on Monterey
It's great that you're taking a cautious approach and seeking advice before adding kexts! Here's how you can get Wifi and Bluetooth working on your Monterey machine with the AR9285 card:
Kexts:
AirportAtheros40.kext: This provides native support for your AR9285 Wifi card.
BrcmPatchRAM2.kext: This is needed for Bluetooth functionality with the AR9285.
Opencore-atheros-kext: This repository contains modified versions of HS80211Family.kext and AirPortAtheros40.kext specifically patched for Opencore and Monterey compatibility. You can choose this instead of the individual kexts mentioned above.
Placement:
OpenCore (OC) kexts folder: Put all kexts (individually or the entire Opencore-atheros-kext folder) in EFI/OC/Kexts.
System Library: You don't need to place any kexts in /System/Library/Extensions for this setup.
Configuration:
OpenCore config.plist:
In the "Kernel" tab, under "Add" > "Patches", add the following configuration:
Type: com.apple.io80211Family
Disable: IO80211PowerManagement.
Under "Boot" > "Arguments", add the following boot argument: bluetoothle=0.